According to a first prior art, for example described in U.S. Pat. No. 7,983,391B2, there is a movable radiation shield reducing radiation exposure. In a volume of interest, only a center part of higher interest is refreshed more often than a surrounding part of lower interest. The radiation detector is not rotating. There is radiation exposure lowering. However, there is no scattered radiation lowering for a given radiation exposure of the volume of interest.
According to a second prior art, for example described in U.S. Pat. No. 8,213,568B2, there is a dynamic collimator shuttering part of the emitted radiation beam to match the beginning and the end of the volume of interest in order to cancel radiation exposure of not needed parts which are just before the beginning of the volume of interest and just after the end of the volume of interest, when performing helical computed tomography. There is cancellation of radiation exposure of useless parts in the vicinity of the volume of interest. However, there is no scattered radiation lowering for a given radiation exposure of the volume of interest.
Several existing imaging methods use collimation variation of emitted radiation beam. But none of them use collimation variation of emitted radiation beam in order to reduce scattered radiation. None of them either use the specific type of collimation variation of emitted radiation beam used in the invention in order to reduce scattered radiation.